This invention relates to steady rests employed to support a cylindrical workpiece for precision machining or grinding. More specifically, this invention relates to a multi-point, true centering steady rest having an internal camming device for adjusting the position of a supported workpiece, both horizontally and vertically.
Steady rests are commonly used to support rotatable cylindrical workpieces for machining or grinding. Steady rests may be found in several of my prior United States patent, including: U.S. Pat. No. 5,285,599 issued Feb. 15, 1994, for xe2x80x9cMethod for Adjusting a Steady Rest having an Internal Centerline Adjustment; U.S. Pat. No. 5,237,780 issued Aug. 24, 1993 for xe2x80x9cSteady Rest with Internal Centerline Adjustmentxe2x80x9d; U.S. Pat. No. 5,058,468 issued Oct. 22, 1991 for xe2x80x9cRemote Gage Steady Rest Headxe2x80x9d; U.S. Pat. No. 4,647,100 issued Mar. 3, 1987 for xe2x80x9cParallel Gripper with Roller Supported Gripper Armsxe2x80x9d; U.S. Pat. No. 4,647,097 issued Mar. 3, 1987 for xe2x80x9cI.D. or O.D. Parallel Gripperxe2x80x9d; and U.S. Pat. No. 4,399,639 issued Aug. 23, 1983 for xe2x80x9cTrue Centering Steady Restxe2x80x9d.
Typically, a steady rest includes a housing mounted on a suitable base adjacent the workpiece. A body in the housing is slidably movable toward or away from the horizontal axis (centerline) of the workpiece, by a hydraulic cylinder. Gripping arms are slidably mounted in a crisscross pattern on the body and move with the body. A wear pad is attached to the outer ends of each of the two arms, and a third wear pad is attached to the body. An internal adjustment means permits the three wear pads to cooperate in providing a three-point gripping arrangement for the workpiece as it is being rotated.
For a variety of reasons explained in my prior patents, the axis of the rotating workpiece may shift a small distance either horizontally or vertically. My prior patents disclose means for adjusting the wear pad locations for a horizontal change in the workpiece axis, without adjusting the steady rest housing.
A need exists for means for making a vertical adjustment of the wear pads without having to adjust the position of the entire steady rest.
The broad purpose of the present invention is to provide an internal camming device for adjusting the vertical position of the wear pads. A preferred steady rest has two internal adjustment features. A vertical adjusting screw permits the user to move a pair of internal, wedge-shaped guides engaging a cam follower carried on each of the gripper arms. The adjusting screw moves one of the guides to an adjusted position. A rocker arm moved by the first guide moves the second guide that cams the second arm. The two guides move in opposite directions along their respective camming surfaces. The result is that the wear pad on one arm will advance horizontally further before it is cammed toward a work contact position. The second wear pad will not move as far forward before it moves toward its work contact position. The geometry of the flat work contact surface of the three wear pads and the cylindrical profile of the workpiece is such that the center of contact of the three wear pads can be adjusted without adjusting the position of the entire steady rest. Reversing the rotation of the adjusting screw adjusts the work contact position of the wear pads in the opposite vertical direction.
A second pair of wedge-shaped guide members, disposed in a side-by-side relationship with the first pair of guide members, engages the same cam followers carried by the two arms. A second, horizontal adjusting screw adjusts the guides to provide a horizontal change in the position of the three wear pads.
Still further objects and advantages of the invention will become readily apparent to those skilled in the art to which the invention pertains upon reference to the following detailed description.